Field of Invention
The present invention relates to an engine cooling system. More particularly, the present invention relates to an engine cooling system for effectively cooling parts of an engine system in which exhaust gas is recirculated by using a turbocharger for improving output in a low speed range.
Description of Related Art
In general, it is known that a diesel engine has lower fuel consumption and better efficiency than a gasoline engine. In general, the diesel engine displays efficiency in a range of 40% owing to a high compression ratio of the diesel engine.
Currently, in order to obtain a high output from the engine, the engine is additionally provided with a turbocharger and an intercooler. The engine having the turbocharger applied thereto takes in exhaust gas or external air through a compressor in the turbocharger and supplies supercharged air (high temperature compressed air) produced thereby to an engine side.
However, the compressed air rapidly absorbs heat from the turbocharger and heat generated in a course of the compression, resulting in lower density and thus poor charging efficiency. Therefore, the supercharged air is cooled by using the intercooler to obtain high density air, resulting in intake of much air into an engine combustion chamber, enabling high output.
In the meantime, in order to meet the current exhaust gas control trend, such as EURO 3 or EURO 4 in Europe, a variety of systems have been suggested in which a portion of the exhaust gas containing CO, HC, NOx, and so on being exhausted from a turbo diesel engine is re-circulated for further reducing contents thereof. Of the systems, typical one is an EGR system (exhaust gas recirculation system).
Along with this, research is underway in which an output torque is increased while reducing the fuel consumption in medium to low speed ranges of engine RPM in the engine having the turbocharger, and research is also underway for making efficient control of the supply of the recirculated gas.
Along with these researches, research is also underway for efficiently cooling an engine system having a turbocharger, an intercooler, and an EGR system.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.